Abstract Integrating results from monitoring efforts conducted across diverse marine ecosystems provides opportunities to reveal novel biogeographic patterns at larger spatial scales and among multiple taxonomic groups. We investigated large-scale patterns of community similarity across major taxonomic groups (invertebrates, fishes or algae) from a range of marine ecosystems (rocky intertidal, sandy intertidal, kelp forest, shallow and deep soft-bottom subtidal) in southern California. Because monitoring sites and methods varied among programs, site data were averaged over larger geographic regions to facilitate comparisons. For the majority of individual community types, locations that were geographically near or environmentally similar to one another tended to have more similar communities. However, our analysis found that this pattern of within community type similarity did not result in all pairs of these community types exhibiting high levels of cross-community congruence. Rocky intertidal algae communities had high levels of congruence with the spatial patterns observed for almost all of the other (fish or invertebrate) community types. This was not surprising given algal distributions are known to be highly influenced by bottom-up factors and they are important as food and habitat for marine fishes and invertebrates. However, relatively few pairwise comparisons of the spatial patterns between a fish community and an invertebrate community yielded significant correlations. These community types are generally comprised of assemblages of higher trophic level species, and additional ecological and anthropogenic factors may have altered their spatial patterns of community similarity. In most cases pairs of invertebrate community types and pairs of fish community types exhibited similar spatial patterns, although there were some notable exceptions. These findings have important implications for the design and interpretation of results of long-term monitoring programs.